The operation of a tractor-trailer upon public highways is a difficult and hazardous job. A considerable amount of skill and training is required to maintain such a wide and long vehicle within the boundaries of a highway lane for long periods of time, over a variety of weather and highway conditions. It is common for the rearwardmost portion of a tractor-trailer to deviate from the boundaries of a highway lane during operation, due to among other factors, the large amount of uncertainty inherent in knowing and controlling the location of such rearwardmost portion of such a long vehicle.
One key factor in maintaining a tractor-trailer within highway lane boundaries is the width of the vehicle. A standard trailer width is between 96 and 102 inches. Another key factor is the length of the trailer. Single box trailers, flatbed trailers, and tanker trailers disposed on a pair of rear axles typically have a length of between 45 and 53 feet, and may be as much as 57 feet in some states. However, on interstate highways, the operation of tandem trailers comprising two or three box trailers is a common practice. Such tandem tractor-trailer assemblies may be as long as 116 feet.
Although interstate highways have a federally mandated minimum lane width of 12 feet, it is common for state highways to be somewhat narrower, and municipal street lanes are almost always narrower. Thus the physical highway lane width is also a key factor in maintaining a tractor-trailer within highway lane boundaries.
In addition, adverse weather and lighting conditions play a significant role as well. In current practice, an operator will attempt to maintain the rear of his vehicle within the traffic lane using rear-view mirrors to observe its location. However, during operation in darkness, with headlight glare from following traffic, it is impossible to accurately make such an observation. In like manner, during adverse weather conditions such as rain or snow, such an observation is not possible due to turbulent mist, snow-obscured lane striping, etc.
Finally, the frequent observation of the rear of the vehicle presents a safety hazard, in that the operator's attention is diverted from the situation in front of the vehicle. The line of sight to a rear-view mirror is nearly perpendicular to the general line of sight forward, and given that each tractor is provided with a passenger side and a driver side mirror, the operator must spend an inordinate amount of time looking over approximately a 180 degree field of view, when his attention would be much more appropriately focused on a field of view of approximately 70 degrees, consisting of the highway and highway shoulders immediately in front of the vehicle. It is also known that the human eye has a greater density of receptor sites on the retina near the focal point of the lens, and that peripheral vision near the focal point of the lens is more rapidly and effectively processed by the brain. Thus, the less an operator relies upon wide-angle peripheral vision in the operation of a tractor-trailer, the better.
There is therefore a need for a reliable, adjustable, inexpensive apparatus, which can be used to indicate the location of the rearwardmost portion of a tractor-trailer, and which can be observed by the operator simultaneously with continued observation of the field of view immediately in front of the tractor trailer. Such a device preferably is retrofittable to existing tractor cabs, is visible during daytime or nighttime operation, and is adjustable to accommodate differences in trailer sizes, highway widths, operators, mounting locations within the tractor cab, and all other variables commonly occurring in the operation of a tractor-trailer. Such an apparatus will simplify and make safer the operation of a tractor-trailer, thereby reducing the stress and anxiety suffered by the operator, thereby making the operator more competent in the overall operation of the rig.
It is therefore an object of this invention to provide a tractor-trailer highway parameter gauge having visual indicators, which correlate with the location of the rearwardmost portion of the tractor-trailer within a traffic lane.
It is a further object of this invention to provide a tractor-trailer highway parameter gauge with visual indicators, which are visible to the operator within the field of view defined by the highway surface in front of the vehicle.
It is another object of this invention to provide a tractor-trailer highway parameter gauge with visual indicators, which are adjustable to accommodate variations in trailer width and highway lane width.
It is a yet another object of this invention to provide a tractor-trailer highway parameter gauge with visual indicators, which are adjustable to accommodate variations in operator height and seating position.
It is a further object of this invention to provide a tractor-trailer highway parameter gauge, which may be installed within the tractor cab.
It is a further object of this invention to provide a tractor-trailer highway parameter gauge, which may be easily installed upon the tractor dashboard, regardless of the angle and surface material of the dashboard.
It is an additional object of this invention to provide a highway parameter gauge, which may be utilized in the operation of car-trailer or light truck-trailer combinations, and which may be used in the operation of trucks having a widthwise-deployable apparatus such as a snowplow.